Field of the Invention
The technical field of the invention is that of a device including a supercapacitor to provide power to start an engine.
Background
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Conventional vehicle engine starting systems may use a battery to supply a starter motor with power to crank a vehicle's engine. However, often times, particularly in cold weather, a battery may not supply sufficient power to the starter to start the engine. Also, the battery may wear overtime after numerous discharges.
Throughout this disclosure reference is made to an energy storage system called “supercapacitor,” also known as “supercapacitance,” or “electrochemical double-layer condenser” and designated as “Electric Double Layer Capacitor (EDLC),” or additionally as “ultracapacitance” and “ultracapacitor.” This is a device allowing energy storage by means of ion accumulation on two electrodes serving as ion collectors when a potential difference is applied between them. The term “supercapacitor” will be used throughout the remainder of this document and it is obvious that this vocabulary also designates the equivalent terminologies mentioned above. An electrochemical supercapacitor comprises at least one positive electrode and at least one negative electrode. Both electrodes are separated from one another by a separator. The electrochemical bundle formed by the assembly of the positive and negative electrodes and the separators is impregnated with an electrolyte.
There are several variations on the design of a supercapacitor. For example, supercapacitors may be symmetric supercapacitors with an aqueous electrolyte, in which the positive electrode and the negative electrode consist of similar materials having the same capacitance. Most often, active carbon is used. Patent application EP-A-1883 937 describes the manufacturing of an electrode based on active carbon which may be used in the design of symmetric supercapacitors with an aqueous electrolyte.
Alternatively, a non-aqueous electrolyte may be used with a symmetric supercapacitor. As described in U.S. Pat. No. 6,356,432, the supercapacitor comprises a non-aqueous electrolyte, such as acetonitrile, and two carbon electrodes, each electrode comprising a binder and an electrochemically active material consisting of active carbon having a specific surface area greater than 2,000 m2/g.
In addition, a supercapacitor may be an asymmetric supercapacitor (or hybrid supercapacitor) with an aqueous electrolyte. Patent application EP-A-1 156 500 describes the general operating principle of this type of supercapacitor. This supercapacitor comprises one negative electrode based on active carbon and one positive electrode whose active material may be reversibly oxidized. The positive electrode is charged by a Faradic process while the negative electrode is charged by ion accumulation at the electrode/electrolyte interface forming a double layer. The charge accumulation occurring at the negative electrode corresponds to a non-Faradic process.